MM-31064: Simplify indentation (#16565)

* MM-31064: Simplify indentation

Reduce indentation where possible.

```release-note
NONE
```

Command ran to verify:
golangci-lint run --disable-all --enable golint --max-issues-per-linter=10000 --max-same-issues=100000 ./... | grep "block ends with a return state"

https://mattermost.atlassian.net/browse/MM-31064

* incorporate review comments

* enable golint for outdent rule

* fix remaining issues

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/post_metadata.go

@@ -534,9 +534,8 @@ func (a *App) parseLinkMetadata(requestURL string, body io.Reader, contentType s
 		// one of these required fields exists before returning the OpenGraph data
 		if og.Title != "" || og.Type != "" || og.URL != "" {
 			return og, nil, nil
-		} else {
-			return nil, nil, nil
 		}
+		return nil, nil, nil
 	} else {
 		// Not an image or web page with OpenGraph information
 		return nil, nil, nil